Screed and divider strip for concrete slabs



Dec. 12, 1967 N. TONE ETAL 3,357,324

SCREED AND DIVIDER STRIP FOR CONCRETE SLABS Filed July 20, 1965 R w 5 MEw m. 7 1. M N W H W E W0 m v. D 5 M m H L 0 5 /4 0 Rw m 5N, E m m ATTORNEYS Importantly,

United States Patent 3,357,324 SCREED AND DIVIDER STRIP FOR CONCRETE SLABS Richard N. Tone, 1803 Mazes Ava, Belmont, Calif. 94002, and Warren D. Wilbur, 13379 Pastel Lane, Mountain View, Calif. 94040 Filed July 20, 1965, Ser. No. 473,352

7 Claims. (Cl. 94-17) ABSTRACT OF THE DISCLOSURE A combination screed and divider strip is disclosed which can be used with a plurality of aligned stakes set at a predetermined grade to enable the pouring and screeding of adjacent slabs of concrete. The screed and divider strip is formed for snap action locking onto the peened over upper ends of the stakes to prevent floating off of the stakes on pouring of the concrete and is formed with a tubular top portion to allow alignment and end-to-end splicing of adjacent strips.

The invention relates to screed and joint forming members for forming and keying concrete slab sections; and more particularly to the type of concrete slab keyjoint forming member disclosed in Wilbur Patent Re. 24,921.

Such screed and joint forming members have come into widespread use due to the many advantages afforded by them. The user will first drive stakes in line along the length of the joint to be formed with the upper ends of the stake set to predetermined grade. This may be conveniently accomplished by tautly drawing a string to the desired grade line and then driving the stakes on the line with the upper ends of the stake driven to the level of the string. The joint member is formed with an inverted channel for slipping over the upper ends of the stake and when supported thereon will present the upper straight edge of the form at finish elevation for screeding of concrete poured against the joint member thus setting the top edge of the joint flush with the top surface of the concrete slab. An adjacent slab section may then be monolithicly poured against the other side of the joint so that a continuous pouring of the concrete slab can take place. the joint is shaped to key the adjacent slab sections together by forming interfitting tongue and groove portions in the abutting sides of the slab thereby permitting relative expansion and contraction of the sections While being maintained in a vertically interlocked condition.

Experience has shown that metal stakes which are used in the present joint should be in the order of at least /a inch thick to stand up to the pounding required for driving of the stakes particularly in hard ground. What happens is that the upper ends of the stakes are peened over in the driving of the stakes which widens the upper edges of the stake with peened over edge flanges. This peening over of the upper ends of the stakes makes full seating of the stake ends at the top of the inverted channel diflicult, if not impossible, with attendant imperfection of alingment of the top edge of the divider strip at finish floor elevation or at grade level.

In certain other instances in the use of joint forming members of the type to which the present invention relates there is a tendency of the joint member to float upwardly in the concrete pour and various constructions have been heretofore proposed for counteracting this tendency wherever it may occur.

An object of the present invention is to provide a screed and divider strip of the character described in which "ice advantage is taken of the peened over form of the upper ends of the stakes to ensure precise mounting of the form member on the stakes to finish grade; and wherein such precise mounting is accomplished automatically with a snap homing action when the form member is properly positioned on the stakes.

Another object of the present invention is to provide a screed and divider strip of the character above wherein the contiguous ends of end-to-end position form members may be quickly and easily held in precise alignment and registration at finish grade so that joints of desired length may be conveniently and effectively produced.

The invention posseses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of this specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawing (one sheet):

FIGURE 1 is a perspective view, partially in crosssection, of a portion of a screed and divider strip constructed in accordance wtih the present invention and illustrated in conjunction with an adjoining concrete slab section formed thereby.

FIGURE 2 is an enlarged fragmentary cross-sectional view of the joint-forming member.

FIGURE 3 is a fragmentary cross-sectional view of contiguous end portions of a pair of end-to-end forms and is taken substantially on the plane of line 3-3 of FIGURE 2, FIGURE 3 being on a reduced scale in relation to FIGURE 2.

A pair of concrete slab key-forming members 11 and 12 are illustrated in the drawing set in end to end abutting relation upon a plurality of stakes driven into the ground at intervals along the length of the joint to be formed. As hereinbefore noted, it is common to stretch a taut level line over the full length of the joint to be formed, the line being here set at predetermined grade level. Steel stakes 13 with flat or flattened tops are driven along the length of the line at intervals of about 2 feet apart with the upper ends 14 of the stakes aligned with and at the level of the string. As also hereinbefore noted, this driving of the stakes into the ground customarily produces peenedover edge flanges 16 and 17. For example, where flat steel stakes having a thickness of about 4; inch are pounded into the ground, the peening of the upper end 14 of the stake will normally widen it with flanges 16 and 17 to about inch or greater.

The screed and divider strip of the present invention is preferably formed of sheet metal and consists briefly of an upper end portion formed with spaced opposed and resiliently displaceable side walls defining an inverted channel for slipping over the stake ends 14, the channel presenting an entry slot 21 somewhat narrower than the width of stake end 14 so as to eflect a resilient separation of side walls 18 and 19 upon effecting entry of the stake into the channel, and the channel is formed with a relatively enlarged socket 22 for snap-acting receipt and retention of stake end 14 when the latter is moved into registration with the socket. Also, importantly, the socket is positioned to locate the top edge 23 of the divider strip at finish floor elevation for screeding of concrete poured adjacently to the divider strip. Preferably, the divider strip is fashioned by roll-forming out of long (approximately 10 feet) lengths of sheet metal by folding a longitudinally extending side portion 26 into spaced opposed relation to the main body portion 27 so as to provide the inverted channel, and socket 22 is formed by rolling a pair of opposed concavo-convex beads 28 and 29 in the channel walls 18 and 19 with the concave sides of the beads confronting each other to provide the socket. Accordingly, the socket extends for the full length of the divider strip and is capable of receiving the upper end 14 of any and all of the stakes set along the length of the divider strip Wherever the stakes may occur over such length.

As a feature of the present construction, the side portion 26 has its lower edge bevelled away from the main body 27 and the main body is formed with a longitudinally extending concavo-convex stiffening rib 32 adjacent the entry slot 21 with its concave side 33 confronting the bevelled edge 31 so as to provide therewith a tapered entryway into the channel for wedging out the side walls 18 and 19. Thus the upper ends 14 of the stakes are conveniently and automatically guided into the channel and as the divider strip is pressed down onto the stakes it will snap home upon them as the stake ends 14 move into socket 22. Because of its shape, the socket is capable of receiving stake ends of various peened over widths as for example /4 inch or even inch. The snap action homing positioning of the stakes in the socket will be the same in all of these instances.

Another feature of the construction of the present divider strip is the provision of a longitudinally extending tubular top section 36 which is formed for receiving an alignment pin at the end of the strip for holding a pair of contiguous strips, such as 11 and 12, in end to end alignment and registration. With reference to FIGURE 2 it will be seen that the top section 36 is arcuately folded to provide opposed semi-circular walls 38 and 39 cooperating to define a circular passageway 41 longitudinally or axially of the tubular top section 36. Preferably the inside diameter of this passage is approximately 0.0625 inch, which will snugly fit a number 16 brad or number 16 rein forcing steel tie wire which is commonly available on construction jobs. Such a brad or wire cut to length to form pin 37 thus inserted into the passage 41 at the contiguous ends 42 and 43 of sections 11 and 12 will positively interlock these sections in end to end alignment at finish grade elevation.

Preferably, the semi-circular walls 38 and 39 defining passageway 41 are brought substantially together at the base 44 of the tubular top section 36 so as to enclose passage 41 and then diverge downwardly therefrom to the socket walls 28 and 29, thus allowing for the spring action of the side walls of the channel. Below socket walls 28 and 29, the channel walls 18 and 19 preferably extend substantially parallel to the entry slot 21 so as to embrace snugly the opposite sides of stake 13.

As will be appreciated, the divider strips of the present invention form the parting faces between adjacent concrete slab sections and the strips are accordingly formed with a longitudinally extending concave-convex portion 46 providing keyed interfitting tongue and groove portions in the parting faces permitting relative expansion and contraction of the sections while being maintained in vertically interlocked condition. Also the main body portion 27 is preferably formed with one or more longitudinally extending stiffening ribs such as ribs 47 and 48 in the base section of the form. As will be observed from FIG- URE 1, this base section is located substantially coplanar with channel side wall 18 so as to lie against and be supported upon the same side of stake 13. Stake 13 may also be formed with a longitudinally extending stiffen- ,ing rib which extends from the lower end 52 of the stake near to the upper end 14, the stiffening rib being foreshortened so as not to enter the mounting channel 21 in the form member. The key portion 46 of the form is also preferably provided with a series of knockout openings 53, for receipt of reinforcing bars where use of the latter is desired.

We claim:

1. In combination, a plurality of aligned metal stakes with peened over upper stake ends set at a predetermined grade level; an elongated sheet metal screed and divider strip having a longitudinally extending side portion folded into spaced opposed relation to the main body of said strip to provide an inverted channel having resiliently displaceable side walls for slipping over said stake ends, said channel presenting an entry slot somewhat narrower than the width of said stake ends so as to effect a resilient separation of said side walls upon effecting entry of said stakes into said channel, said channel being formed with a relatively enlarged socket extending longitudinally over the length of said strip for snap acting receipt and retention of said stake ends, and said strip being mounted on said stakes with said stake ends registering with said socket, said socket being positioned to locate the top edge of said divider strip at finish elevation for screening of concrete poured adjacent to said divider strip.

2. The combination of claim 1 wherein said side portion has its edge bevelled away from said main body and said main body is formed with a longitudinally extending concave-convex stiffening rib adjacent said entry slot and with its concave side opposed to said bevelled edge to provide therewith a tapered entryway to said channel for wedging out said side walls.

3. In combination, a plurality of aligned metal stakes With peened over upper stake ends set at a predetermined grade level; an elongated sheet metal screed and divider strip having a longitudinally extending side portion folded into spaced opposed relation to the main body of said strip to provide a longitudinally extending tubular top section and a subjacent inverted channel section, said channel section having resiliently displaceable side walls for slipping over said stake ends and presenting an entry slot somewhat narrower than the width of said stake ends so as to eifect a resilient separation of said side walls upon effecting entry of said stakes into said channel, said channel being formed with a relatively enlarged socket extending longitudinally over the length of said strip for snap acting receipt and retention of said stake ends, said strip being mounted on said stakes with said stake ends registering with said socket, said socket being positioned to locate the upper edge of said divider strip at finish elevation for screeding of concrete poured adjacent to said divider strip, said tubular top section being formed for receiving an alignment pin at the end of said strip for holding contiguous strips in end to end alignment and registration.

4. The combination of claim 3 wherein said side portion and adjacent main body portion are arcuately folded to provide opposed substantially semi-circular walls cooperatively defining said tubular section and being sub stantially closed together at the base of said section and diverging downwardly therefrom to said socket and continuing downwardly to provide the Walls of said channel, said channel walls being substantially parallel from.- said socket to said entry slot, and at least one of said walls bevelling outwardly away from the other below said slot to provide a tapered entryway to said channel for wedging apart of said walls.

5. A screed and divider strip comprising, an elongated sheet strip having a longitudinally extending side portion formed in spaced opposed relation to the main body of said strip to provide an inverted channel section for slipping over the upper ends of aligned stakes driven into the ground at predetermined grade level, said sheet being formed of resilient material for resilient springing of said portion and opposed body to and from each other, said channel section being formed with an entry slot for receiving said upper ends of said stakes and said slot being narrowed relative to the width of the adjacent channel portion to effect a snap acting entry into said channel portion and retention therein of peened over upper ends of said stakes, said side portion having its lower edge bevelled away from said main body and said main body being formed with a longitudinally extending concave-convex stiffening rib adjacent said entry slot with its concave side opposed to said bevelled edge to provide therewith a tapered entry Way for Wedging out the opposed sides of said slot by said stake ends.

6. A screed and divider joint for concrete slab comprising, a plurality of ground stakes set in alignment and predetermined grade level, a plurality of elongated sheet metal strips each having a longitudinally extending side portion formed in spaced opposed relation to the main body of said strip to provide therewith a longitudinally extending tubular top section and subjacent inverted channel section, said channel sections mounted on and supported by said stakes with said strips in contiguous end to end positions and with the upper surface of said tubular top sections at substantially finish grade, and an alignment pin mounted in said tubular top sections for holding said strips in end to end alignment and registration.

7. A screed and divider joint as defined in claim 6, wherein said stakes have peened over upper ends, and said channel section is formed with an entry slot for re ceiving said stake ends and said slot is narrowed relative to the Width of an adjacent portion of said channel to effect a snap-acting entry into said channel portion and retention therein of said stake ends.

References Cited UNITED STATES PATENTS 1,978,305 10/1934 Hall 9418 2,039,144 4/1936 Burgess 9417 2,040,367 5/ 1936 Eichelman 94-18 3,143,783 8/1964 Gaetke 9451 JACOB L. NACKENOFF, Primary Examiner. 

1. IN COMBINATION, A PLURALITY OF ALIGNED METAL STAKES WITH PEENED OVER UPPER STAKE ENDS SET AT A PREDETERMINED GRADE LEVEL; AN ELONGATED SHEET SCREED AND DIVIDER STRIP HAVING A LONGITUDINALLY EXTENDING SIDE PORTION FOLDED INTO SPACED OPPOSED RELATION TO THE MAIN BODY OF SAID STRIP TO PROVIDE AN INVERTED CHANNEL HAVING RESILIENTLY DISPLACEABLE SIDE WALLS FOR SLIPPING OVER SAID STAKE ENDS, SAID CHANNEL PRESENTING AN ENTRY SLOT SOMEWHAT NARROWER THAN THE WIDTH OF SAID STAKE ENDS SO AS TO EFFECT A RESILIENT SEPARATION OF SAID SIDE WALLS UPON EFFECTING ENTRY OF SAID 